Method of making copper-cadmium alloy



but approximately 5 to 15 per cent.

TED STATES PATENT OFFICE.

WALTER C. SMITH, OF ROSEL'LE, NEW JERSEY, ASSIGNOR TO UNITED STATES SMELT- ING, REFINING & MINING COMPANY, A CORPORATION OF MAINE.

METHOD OF MAKING GOITERFCADMIUM ALLOY.

No Drawing.

To all whom it may concern:

Be it known that I, WALTER C. SMITH, a citizen of the United States, residing at Roselle, in the county of Union and State of New J ersey, have invented certain new and useful Improvements in Methods of Making Copper-Cadmium Alloy; and I do hereby declare clear, and exactdescription of the invention, such as will enable others skilled in the art to which it appertains to make and use the same. v

The invention relates to the production of copper cadmium alloys.

It has been found that the addition of a small amount of cadmium (say from 1} to 1.1 per cent.) to copper which does not in juriously affect its doubles its tensile strength at ordinary'temperatures, while reducing its conductivity A copper cadmium alloy having a small percentage of cadmium is therefore well adapted for the manufacture of wire for use as electric conductors, particularly under conditions where the available supports may be widely separated. The usual methods of unsuited to the production of copper cac mium alloy containing an approximate definite percentage of cadmium, owing to the characteristics of cadmium which cause its rapid volatilization and oxidation when added to a molten copper bath with such resulting rapid and variable losses of cadmium as to preclude the production of even an approximately uniform alloy. It is the primary object f the present invention in its entirety to provide for the commercial production of a copper cadmium alloy containing a comparatively low percentage of cadmium. The complete method by which producing copper, alloys are however wholly y i such production is rendered feasible includes two stages, each of which. constitutes a feature of the invention, and by each of which a copper cadmium alloy of substantially uniform and known composition may be roduced.

he method or sub-method comprising the first stage is used to produce an alloy o. meltingpoint of which is below the boiling oint of cadmium, andconsequently containing a higherpercentage of cadmium than the following to be a full,

ductility approximately to the bath, either results.

Specification of Letters Patent. Patented J 11119 24, 1919, Application filed August 15, 1918. Serial No. 249,924.

should be present in an alloy to be used in the manufacture of electric wires, since the melting points of alloys containing less than 5 per cent. of cadmium are above the boiling A small quantity of an point of cadmium.

high percentage of alloy having a known cadmium (say per cent. or more) such as may be produced by the first stage is utilized in the method or sub-method of the second stage to produce an alloy having a low percentage of cadmium and therefore well adapted for the uses above indicated.

To produce the high-percentage cadmium alloy with comparatively little and approximately unvarying loss of cadmium, the temperature and the melting-point of a molten bath of copper are simultaneously and quickly reduced to a point below the boiling point of cadmium by adding solid cadmium as a'metal or as a highpercentage cadmium alloy. The heat absorbed in meltin the cadmium (or alloy) rapidly reduces tfie temperature of the bath, while the melting point of the alloy produced by the mixture of the cadmium and the copper rapidly falls as the proportion of the cadmium increases. The addition of between five and seven per cent. in weight of cadmium to the copper bath should reduce its temperature and its melting point to a temperature below the boiling point of cadmium, (about 700 C.) During the addition of this amount of cadmium there will of course be more or less loss, 'due to its volatilization during the interval in which the temperature of the bath remains above the boiling point of the cadmium. The cadmium should therefore be added as'rapidly as is practicable, and in proper condition as to size and distribution of pieces or lumps to avoid freezing the bath. The supply of heat to the 'bath should also be \shut oif before addin the cadmium to secure the best- T us far the method will give a copper cadmium alloy having between 5 and 10 per cent. of cadmium. If an alloy having a higher percentage of cadmium is desired, as will be the case if the alloy is to be used in making a low percentage alloy in accordance with the second stage of the invention, the additional cadmium required is added to the bath while maintaining the from thirty to seventy-five.

temperature of the bath between its melting point and the boiling point of cadmium. As soon as the cadmium is melted and thoroughly mixed with the copper, the bath is cast into solid form. I

.While the cadmium may be added either as a metal or as an alloy, it is better practice to add to the copper bath a sutlicient amount of previously made alloy having a high percentage of cadmium, to bring the ten'lperature of the bath below the boiling point of cadmium, since this will result in less violent disturbance in the bath and less loss may be reduced or loss of cadmium. After the temperature of the bath has been thus reduced below the boilingpoint of cadmium, the percentage of cadmium in the bath may best be brought up to the point desired by adding cadmium metal. The-temperature ofthe bath, even after it has been reduced below the boiling point of cadmium, is still above that at which cadmium will burn (about 350 (1.), and consequently there maybe some loss of cadmium, due to oxidation and burning during the addition of the cadmium and the stirring of the bath to thoroughly mix the alloy or the cadmium with the copper. This prevented by protecting the bath with a molten cover of neutral material, such as a flux, by powdered charcoal, or other suitable cover, which will prevent oxidation and burning ofthecad- ,mium at the surface of the bath. To produce an alloy having a comparatively low percentage of cadmium, and con- 'sequently a melting point above the boiling -point of cadmium, a comparatively small quantlty of copper cadmium alloy having a comparatively high percentage of cadmium is added 'to a molten. bath of copper, the re tsulting alloy being cast as soon as possible after themelting. and mixing of the added alloy'. Thdperceritage of cadmium in the added'alloys-should 'be so high that the quantity requisite to secure the desired per- -;.-,c entage of cadmium in the bath will be at small vproportion of the bath, since to avoid i j loss-of cadmium the added alloys should be melted intheleast possible time by the abwitha molten material, or with a protective coverlng of sorption of heat from the bath. iSatisfacatory results have been obtained by the use of alloys havlng from 30 to 75 per cent. of cadmium. Loss of cadmium, due to oxidationand burning at the surface of the bath, may be prevented or reduced, as in the first stage of the method, by providing the bath protective covering of neutral" powdered charcoal. a

In utilization of the ,method for the production of, a copper cadmium alloy for use in the manufacture of electric-conductor wire, it will probably be found undesirable to produce an alloy having more than 1.1 per I d d 0 cent. cadmium, since an increase 111 the perper cent. cadmium has given the most satisfactory results. In producing alloy for electric wires care should be taken that no zinc nor tin are present in the copper bath, since the presence of these metals, even in small quantities, materially lowers the conductivity of the alloy. If the low percentage cadmium alloy is not to be used for the manufacture of electric conductors, the presence of more than 1.1 per cent. of cadmium or the presence of small quantities of zinc or tin, or

possibly other metals, in the alloy produced may not be undesirable.

- What is claimed is 1. The method of making copper cadmium alloy which consists in simultaneously reducing the temperature and the melting point of a molten copper bath to a temperature below the boiling point of cadmium by the addition thereto of cadmium in a solid state, thereafter continuing the addition of cadmium while maintaining the bath at a temperature above its melting point and below the boiling point of cadmium, solidify: ing the resultingalloy, and thereafter adding to a. molten bath of copper a quantity of the solidified alloy which is a small proportion of the total bath.

2. The method of making copper cadmium alloy which consists in simultaneously reducing the temperature and the melting 100 point of a molten copper bath to a-temperature below the boiling point of cadmium by the addition thereto, of cadmium in a solid state, thereafter continuing the addition of cadmium while maintaining the bath at a temperature above its melting point and below the boiling pointfof cadmium until the bath contains a comparatively high percentage of cadmium (say thirty to'seventyfive per cent. or more), solidifying the r sulting alloy, .and thereafter adding to a molten copper bath a quantity of the high percentage alloy 'sufliclently small to be melted by heatjabsorbed. from the bath and thereby produce an alloy having a comparatively low percentage of cadmium, (sayone point of a molten copper bath to a tempera-- ture below the boiling point of cadmium by the addition thereto of a solid alloy having a high percentage of cadmium.

(i. The method of making copper cadmlum alloy which cOnSlStS 1n slmultal'ieously reducing the temperature and the melting" point of a molten copper bath to a temperature below the boiling point of cadmium by the addition thereto of 'a solid alloy having a high percentage of cadmium, and thereafter continuing the addition of cadmium to the bath while maintaining the bath at a temperature above its melting point and below the boiling point of cadmium.

7. The method of making copper cadmium allo which consists in providing a molten bath of copper with a neutral cover, and simultaneously reducing the temperature and the melting point of the bath to a temperature below the boiling point of cadmium y the addition thereto of cadmium in a solid state.

8. The method of making copper cadmium alloy which consists in adding to a molten bath of copper, cadmium in a solid state sufficiently small in quantity to be melted by heat absorbed from the bath and sufficiently high in cadmium to reduce the temperature of the bath to a point below the boiling point of cadmium and above the melting point of the resulting bath.

9. The method of making copper cadmium alloy which consists in adding to a molten bath of copper solid cadmium alloy having a high percentage of cadmium insuch small quantity that the added alloy may be melted by heat absorbed from the bath.

10. The method of making copper ca dmium alloy which consists in providing a molten bath of copper with a neutral cover and adding to the bath solid copper cadmium alloyhaving a high percentage of cadmium in such small quantity that the added alloy may be melted by heat absorbed from he bath.

VALTER- C. ShflTH. 

